6mm CM v .243 Win = zero sum game with the same twist barrel. Here's a little Wiki extract regarding pressure:
After the 6.5mm Creedmoor was introduced, it was advertised as a 60,000 psi capable case.[7] However, after it was placed into production, Hornady listed it as 62,000 psi, then registered it with SAAMI as such. For this reason, many hand loaders have poor experiences reloading for it. Blown primers on the first shot at 62,000 psi are not uncommon. Early shooting articles listed the ammo as loaded to 58,000 psi[21], but later citings list it as 57,000 psi.[22] Hornady reduced the loads in its factory ammo because of complaints it was often blowing primers.[23]
Bookmarks